Work out in person (6)
I believe the answer is:
figure
This clue is a double definition.
'work out' is the first definition.
(I've seen this before)
'person' is the second definition.
(figure is a kind of person)
'in' acts as a link.
(Other definitions for figure that I've seen before include "Judge to be probable, estimate" , "Person's bodily shape" , "Work out" , "Number; statue" , "Come to understand - shape" .)